EP 1 036613 B1 discloses the basic structural design of such an immersion nozzle. The immersion nozzle encompasses a tubular body and a pouring channel, which extends from a first end section of the tubular body, where a metal melt enters the pouring channel, to a second end section, where the metal melt exits the pouring channel via at least one outlet opening. As evident from the publication, immersion nozzles, with two diametrically opposed lateral outlet openings are encompassed by prior art, so that the melt is laterally diverted in two directions from an initially purely vertical flow direction before exiting the Immersion tube.
In generic nozzles, it is known to supply an inert gas like argon to the metal melt, for example so is to prevent so-called “clogging”, i.e., to prevent growths from narrowing the cross section of the pouring channel.
The disadvantage to this process is that gas bubbles of significant size form in part, and are entrained in the metallurgical molten bath with the melt stream. Such gas bubbles can exhibit a diameter of several millimeters, but at times diameters in the centimeter range as well.
As soon as the melt is transferred from the immersion tube into the molten bath of the metallurgical vessel (for example, an ingot mold of a continuous casting system), especially large gas bubbles bubble up in the molten bath, but additional problems are here encountered as well:                Turbulences arise in the transitional area between the immersion tube and the melt bath, negatively influencing wear of the immersion tube;        The casting level (surface of the melt bath) can fluctuate, in particular in the contact zone relative to the immersion tube;        The slag can foam;        Rising gas bubbles can break up a slag layer lying on the melt bath and/or a casting powder layer. The melt may undesirably come into contact with the ambient air in the process. Slag can also be drawn into the melt.        
Zhang et. al. “Physical, Numerical and Industrial Investigation of fluid Flow and Steel Cleanliness in the Continuous Casting Mold at Panzhihua Steel” describe the flow conditions in immersion tubes when gas is injected in AIS Tech 2004, Nashville (US), Sep. 15-17, 2004, Association Iron Steel Technology, Warrendale, Pa. (US), 879-894. Under certain operating conditions, gas and melt separate. This yields in part very large gas bubbles, which exit the immersion tube and penetrate into the melt.